Process for producing fluorinated alkylamine compound

ABSTRACT

F(CF 2 ) n (CH 2 ) m NH 2  is produced in high yield, while reducing the amount of by-products contained in the reaction product and preventing the reactor from corroding. Provided is a process for producing a fluorinated alkylamine compound, which comprises reacting a compound represented by F(CF 2 ) n (CH 2 ) m X (wherein X represents a chlorine atom, a bromine atom or an iodine atom, and n and m each independently represents an integer of at least 1) with NH 3  to produce a compound represented by F(CF 2 ) n (CH 2 ) m NH 2  (wherein n and m have the same meanings as the above), and is characterized by conducting the reaction in the presence of a reaction solvent comprising an alkanediol as an essential component.

TECHNICAL FIELD

[0001] The present invention relates to a process for producing a fluorinated alkylamine represented by F(CF₂)_(n)(CH₂)_(m)NH₂.

BACKGROUND ART

[0002] A fluorinated alkylamine compound represented by F(CF₂)_(n)(CH₂)_(m)NH₂ is a compound useful as a starting material for the synthesis of various organic compounds. Particularly, CF₃CH₂NH₂ is a compound which is important as e.g. an intermediate for the synthesis of pharmaceuticals and agricultural chemicals.

[0003] As a method for producing F(CF₂)_(n)(CH₂)_(m)NH₂ by reacting F(CF₂)N(CH₂)_(m)X with NH₃, (1) a method for producing CF₃CH₂NH₂ by reacting from 1 to 3 times by mol of NH₃ to CF₃CH₂X in the presence of an inert solvent such as anhydrous N-methylpyrrolidone or anhydrous glycol (U.S. Pat. No. 4,618,718), (2) a method for producing CF₃CH₂NH₂ by reacting CF₃CH₂Cl with concentrated aqueous ammonia, wherein from 1 to 3 times by mol of NH₃ is used relative to CF₃CH₂Cl (U.S. Pat. No. 2,348,321) or (3) a method for producing CF₃CH₂NH₂ by reacting CF₃CH₂Cl or CF₃CH₂Br with concentrated aqueous ammonia, wherein 6.5 times by mol of NH₃ is used relative to CF₂CH₂Cl or CF₃CH₂Br (Dickey et al, Ind. Eng. Chem., Vol. 48,209, 1956), is, for example, known.

[0004] However, in the method (1), the reaction is carried out under an industrially disadvantageous high reaction pressure (7 to 11 MPa), and it is disclosed that if the pressure is lowered, the yield of CF₃CH₂NH₂ decreases. Further, when a duplicate test was carried out in accordance with the method (1), a problem was observed such that a part of CF₃CH₂NH₂ was reacted with HX formed as a by-product, to form a halogenated salt (CF₃CH₂NH₂.HX), whereby the yield of CF₃CH₂NH₂ decreased (to a level of from 70 to 87%). Further, in order to convert the formed CF₃CH₂NH₂.HX to CF₃CH₂NH₂ for recovery, it is necessary to add an aqueous alkali solution and to carry out extraction with an organic solvent, followed by distillation for purification, thus leading to a problem that the number of process steps increases, and the process becomes cumbersome. Further, there has been an additional problem that part of the formed CF₃CH₂NH₂ reacts with CF₃CH₂X to from a secondary amine compound represented by (CF₃CH₂)₂NH or a tertiary amine compound represented by (CF₃CH₂)₃N, whereby the yield of CF₃CH₂NH₂ tends to be low.

[0005] Further, in the method (2) or (3), no organic solvent is employed, and concentrated aqueous ammonia is used as a reaction solvent. CF₃CH₂X is hardly soluble in concentrated aqueous ammonia, whereby the reactivity with NH₃ tends to be low, and a problem that the yield tends to be low, was observed. Further, when the method (2) or (3) was practically employed, it was necessary to use an expensive reactor made of a corrosion resistant material such as hastelloy, since there was a problem of corrosion of the reactor.

DISCLOSURE OF THE INVENTION

[0006] The present invention has been made to solve the above problems and provides a process for producing a fluorinated alkylamine compound, which comprises reacting a compound represented by F(CF₂)_(n)(CH₂)_(m)X (wherein X represents a chlorine atom, a bromine atom or an iodine atom, and n and m each independently represents an integer of at least 1) with NH₃ to produce a compound represented by F(CF₂)_(n)(CH₂)_(m)NH₂ (wherein n and m have the same meanings as the above), and is characterized by conducting the reaction in the presence of a reaction solvent comprising an alkanediol as an essential component.

BEST MODE FOR CARRYING OUT THE INVENTION

[0007] In F(CF₂)_(n)(CH₂)_(m)X in the present invention, X is preferably a chlorine atom from the viewpoint of the availability, the reactivity, etc. Further, n is preferably from 1 to 16, more preferably from 1 to 8, particularly preferably 1. m is preferably from 1 to 10, more preferably from 1 to 5, particularly preferably 1. The following compounds may be mentioned as specific examples of F(CF₂)_(n)(CH₂)_(m)X.

[0008] CF₃CH₂Cl, CF₃CH₂Br, CF₃CH₂I, CF₃CF₂CH₂Cl, CF₃CF₂CH₂Br, CF₃CF₂CH₂I, F(CF₂)₃CH₂Cl, F(CF₂)₄CH₂Cl, F(CF₂)₅CH₂Cl, F(CF₂)₆CH₂Cl, F(CF₂)₇CH₂Cl, F(CF₂)₈CH₂Cl.

[0009] CF₃(CH₂)₂Cl, CF₃(CH₂)₂Br, CF₃(CH₂)₂I, CF₃CF₂(CH₂)₂Cl, CF₃CF₂(CH₂)₂Br, CF₃CF₂(CH₂)₂I, F(CF₂)₃(CH₂)₂Cl, F(CF₂)₄(CH₂)₂Cl, F(CF₂)₅(CH₂)₂Cl, F(CF₂)₆(CH₂)₂Cl, F(CF₂)₇(CH₂)₂Cl, F(CF₂)₈(CH₂)₂Cl.

[0010] CF₃(CH₂)₃Cl, CF₃(CH₂)₃Br, CF₃(CH₂)₃I, CF₃CF₂(CH₂)₃Cl, CF₃CF₂(CH₂)₃Br, CF₃CF₂(CH₂)₃I, F(CF₂)₄(CH₂)₃Cl, F(CF₂)₄(CH₂)₃Cl, F(CF₂)₅(CH₂)₃Cl, F(CF₂)₆(CH₂)₃Cl, F(CF₂)₇(CH₂)₃Cl, F(CF₂)8(CH₂)₃Cl.

[0011] In the present invention, at the time of reacting F(CF₂)_(n)(CH₂)_(m)X with NH₃, a solvent comprising an alkanediol as an essential component, is used. As the alkanediol, a C₂₋₁₀ alkanediol is preferred for the reason of handling efficiency and the physical properties of the solvent. Further, as such an alkanediol, octane-1,8-diol, propylene glycol or ethylene glycol is preferred. Further, propylene glycol or ethylene glycol is particularly preferred, since the effects of the present invention are thereby distinctly observed.

[0012] Further, the reaction solvent preferably consists essentially of an alkanediol or essentially of an alkanediol and water. Particularly preferred is a reaction solvent consisting essentially of at least one member selected from propylene glycol and ethylene glycol, or a reaction solvent consisting essentially of at least one member selected from propylene glycol and ethylene glycol, and water. Especially preferred is a reaction solvent consisting of at least one member selected from propylene glycol and ethylene glycol. When water is present in the solvent, the total amount of the alkanediol is preferably at least 1 mass %, more preferably at least 10 mass %, relative to water.

[0013] The alkanediol is believed to have an activity to increase the solubility of F(CF₂)_(n)(CH₂)_(m)X and the reactivity of NH₃ with F(CF₂)_(n)(CH₂)_(m)X. If the proportion of the alkanediol in the reaction solvent becomes large, there will be an effect such that the yield of the fluorinated alkylamine compound will be remarkably high. Further, by using the alkanediol, F(CH₂)_(n)(CH₂)_(m)NH₂ will be formed in high yield even when the reaction pressure is adjusted to be low. Further, corrosion of the reactor can be prevented by using the alkanediol.

[0014] If the amount of the reaction solvent is too much, the volume efficiency of the reactor tends to be poor, and there will be a drawback that the productivity decreases. On the other hand, if the amount of the reaction solvent is too small, NH₃ and F(CF₂)_(n)(CH₂)_(m)X tend not to sufficiently be dissolved in the reaction solvent, whereby an industrially disadvantageous high reaction pressure will have to be used. Accordingly, the amount of the reaction solvent is preferably from 0.5 to 50 times by mass, more preferably from 1 to 20 times by mass, relative to F(CF₂)_(n)(CH₂)_(m)X.

[0015] In the present invention, at the time of reacting F(CF₂)_(n)(CH₂)_(m)X with NH₃, it is preferred to employ at least 4 times by mol of NH₃ relative to F(CF₂)_(n)(CH₂)_(m)X. Namely, HX as a by-product (HX) in the reaction of F(CF₂)_(n)(CH₂)_(m)X with NH₃, will further react with NH₃ to form NH₄X, but if the amount of NH₃ is small, HX will also react with F(CF₂)_(n)(CH₂)_(m)NH₂ to form F(CF₂)_(n)(CH₂)_(m)NH₂.HX. However, by adjusting the amount of NH₃ to be at least a certain specific level, the amount of formation of F(CF₂)_(n)(CH₂)_(m)NH₂.HX can be remarkably reduced. This is considered to be such that excessively present NH₃ has a function to convert F(CF₂)_(n)(CH₂)_(m)NH₂.HX to F(CF₂)_(n)(CH₂)_(m)NH₂.

[0016] On the other hand, if the amount of NH₃ is too much, the reaction pressure will be high, and there will be a problem such that unreacted NH₃ will remain, or the operation efficiency and economical efficiency tend to be low. From the foregoing reasons, the amount of NH₃ is more preferably from 4 to 10 times by mol, particularly preferably from 4 to 6 times by mol, relative to F(CF₂)_(n)(CH₂)_(m)X.

[0017] Further, it is considered that if NH₃ is present excessively, NH₃ will also suppress a side reaction to form a secondary amine compound or a tertiary amine compound. Further, the alkanediol to be used as the reaction solvent, is considered to suppress such a side reaction by promoting the reaction of F(CF₂)_(n)(CH₂)_(m)X with NH₃.

[0018] In the reaction of the present invention, the reaction temperature is preferably from 30 to 250° C., more preferably from 150 to 250° C., particularly preferably from 170 to 210° C. The reaction temperature may not necessarily be constant and may preferably be changed as the case requires.

[0019] Further, it is preferred that the reaction pressure is suitably changed by adjusting the supply ratio of the reaction solvent and F(CF₂)_(n)(CH₂)_(m)X. Usually, it is preferably from 0.5 to 10 MPa (gauge pressure, hereinafter represented by a gauge pressure, unless otherwise specified), more preferably from 0.5 to 5 MPa, particularly preferably from 1 to 5 MPa, most preferably from 1 to 3 MPa. If the amount of the reaction solvent is large, the reaction pressure decreases, and if it is small, the reaction pressure increases. Further, if the reaction pressure is too high, such is disadvantageous from the viewpoint of the operation efficiency and capital investment, and if it is too low, no adequate reaction rate tends to be obtained. In the present invention, the product can be obtained in good yield even under low pressure, by using the alkanediol as the solvent

[0020] By the reaction of the present invention, a fluorinated alkylamine compound represented by F(CF₂)_(n)(CH₂)mNH₂ is formed. In the compound, n and m are the same as n and m in the starting material. The following compounds may be mentioned as specific examples of the fluorinated alkylamine compound.

[0021] CF₃CH₂NH₂, CF₃CF₂CH₂NH₂, F(CF₂)₃CH₂NH₂, F(CF₂)₄CH₂NH₂, F(CF₂)₅CH₂NH₂, F(CF₂)₆CH₂NH₂, F(CF₂)₇CH₂NH₂, F(CF₂)₈CH₂NH₂.

[0022] CF₃(CH₂)₂NH₂, CF₃CF₂(CH₂)₂NH₂, F(CF₂)₃(CH₂)₂NH₂, F(CF₂)₄(CH₂)₂NH₂, F(CF₂)₅(CH₂)₂NH₂, F(CF₂)₆(CH₂)₂NH₂, F(CF₂)₇(CH₂)₂NH₂, F(CF₂)₈(CH₂)₂NH₂.

[0023] CF₃(CH₂)₃NH₂, CF₃CF₂(CH₂)₃NH₂, F(CF₂)₃(CH₂)₃NH₂, F(CF₂)₄(CH₂)₃NH₂, F(CF₂)₅(CH₂)₃NH₂, F(CF₂)₆(CH₂)₃NH₂, F(CF₂)₇(CH₂)₃NH₂, F(CF₂)₈(CH₂)₃NH₂.

[0024] The reaction of the present invention is carried out preferably by introducing the reaction solvent, F(CF₂)_(n)(CH₂)_(m)X and NH₃ into a reactor by a batch system or a continuous system and dissolving the compounds in the reaction system in the reaction solvent. The timing for introducing NH₃ and F(CF₂)_(n)(CH₂)_(m)X is not particularly limited, and a method of charging all the amounts all at once preliminarily before the reaction, a method of continuously supplying them during the reaction, or a method of dividedly supplying them during the reaction, may, for example, be mentioned.

[0025] Further, at the initial stage of the reaction, the reaction may be carried out by a small amount of NH₃, and at the final stage of the reaction, the reaction may be carried out by supplying a large amount of NH₃. Here, if the amount of NH₃ used at the initial stage of the reaction is small, (CF₂)_(n)(CH₂)_(m)NH₂.HX may be formed, but even in such a case, by supplying NH₃ in a large amount at the final stage of the reaction, it is possible to reduce the amount of formation of F(CF₂)_(n)(CH₂)_(m)NH₂.HX and increase the yield of the desired compound.

[0026] In the reaction of the present invention, the conversion and selectivity are high, whereby a reaction crude product containing the fluorinated alkylamine compound obtained by the reaction can be made to be a fluorinated alkylamine compound of high purity by a simple purification operation. For example, by subjecting the reaction crude product to purification by distillation as it is, it is possible to recover F(CF₂)_(n)(CH₂)_(m)NH₂ of high purity. At the time of the distillation, it is preferred to maintain the condenser temperature to a level lower by at least 10° C. than the boiling point of F(CF₂)_(n)(CH₂)_(m)NH₂ in order to prevent a decrease in the recovery rate by discharge of F(CF₂)_(n)(CH₂)_(m)NH₂ together with NH₃. Further, the pressure during the distillation is preferably adjusted to be at least 0.1 MPa (absolute pressure).

[0027] The fluorinated alkylamine compound is a compound useful as a starting material for the synthesis of various organic compounds. For example, CF₃CH₂NH₂ is a compound which is important as an intermediate for the synthesis of therapeutic agents for osteoporosis, cancer, etc., or as an intermediate for the synthesis of agricultural chemicals.

EXAMPLES

[0028] Now, specific embodiments of the present invention will be described in detail with reference to Examples. However, the present invention is by no means restricted thereto. The analysis of products was carried out by gas chromatography (GC) and ¹⁹F-NMR, and the ratios of components in Table 1 are values converted to mol %. Further, the ratio of other components in Table 1 was calculated by using a mol factor of CF₃CH₂Cl.

Example 1

[0029] Into a pressure stirring type autoclave made of stainless steel and having a capacity of 200 ml, 0.15 mol of CF₃CH₂Cl, 0.4 mol (2.7 times by mol relative to CF₃CH₂Cl) of anhydrous ammonia and 0.8 mol (5.3 times by mol relative to CF₃CH₂Cl) of propylene glycol, were charged and stirred at 180° C. for 48 hours to carry out the reaction. The pressure in the autoclave was initially 1.2 MPa, but decreased to 1.0 MPa at the termination. After the termination of the reaction, the autoclave was cooled to 120° C., and the gas component in the autoclave was purged via a condenser, and the gas component containing CF₃CH₂NH₂ was collected by a cooling trap. On the other hand, in the autoclave, 100 g of water was added to have the residual substances dissolved, and the internal standard was added to the dissolved substances, whereupon ¹⁹F-NMR was measured to quantitatively analyze CF₃CH₂NH₂.HX. The substances collected by the cooling trap and the content of the autoclave were analyzed, and the results are shown in Table 1. After the reaction, no substantial corrosion of the reactor was observed.

Example 2

[0030] The reaction was carried out in the same manner as in Example 1 except that anhydrous ammonia was increased to 0.6 mol (4.0 times by mol relative to CF₃CH₂Cl). The reaction pressure was initially 2.0 MPa, but decreased to 1.5 MPa at the termination. Products were analyzed, and the results are shown in Table 1. After the reaction, no corrosion of the reactor was observed.

Example 3

[0031] Into a pressure stirring type autoclave made of stainless steel and having a capacity of 200 ml, 0.15 mol of CF₃CH₂Cl, 0.6 mol (4 times by mol relative to CF₃CH₂Cl) of anhydrous ammonia, and 1.2 mols (8 times by mol relative to CF₃CH₂C1) of propylene glycol, were charged, and stirred at 200° C. for 48 hours to carry out the reaction. The pressure in the autoclave was 2.2 MPa at the initial stage of the reaction, but decreased to 1.7 MPa at the termination of the reaction. After termination of the reaction, the autoclave was cooled to 120° C., and the gas component in the autoclave was purged via a condenser, and the gas component containing CF₃CH₂NH₂ was collected by a cooling trap. The substances collected by the cooling trap and the content of the autoclave were analyzed, and the results are shown in Table 1. After the reaction, no substantial corrosion of the reactor was observed.

Example 4

[0032] Into a pressure stirring type autoclave made of stainless steel and having a capacity of 2,000 ml, 1.5 mols of CF₃CH₂Cl, 6 mols (4 times by mol relative to CF₃CH₂Cl) of anhydrous ammonia, and 12 mols (8 times by mol relative to CF₃CH₂Cl) of propylene glycol, were charged and stirred at 200° C. for 48 hours to carry out the reaction. The reaction pressure was initially 2.2 MPa, but decreased to 1.7 MPa at the termination. After termination of the reaction, the autoclave was cooled to 10° C. The reaction crude product recovered from the autoclave was analyzed. As a result, the conversion was 97.5%, and the selectivity for CF₃CH₂NH₂ was 97.8%. Further, the reaction crude product was subjected to purification by distillation under atmospheric pressure at −20° C. (the condenser temperature) to obtain a fraction. The fraction was analyzed, and the results are shown in Table 1. After the reaction, no substantial corrosion of the reactor was observed.

Example 5

[0033] The reaction was carried out in the same manner as in Example 3 by changing 1.2 mols of propylene glycol to 1.2 mols of ethylene glycol. The reaction pressure was initially 2.1 MPa, but decreased to 1.6 MPa at the termination. The products were analyzed, and the results are shown in Table 1. After the reaction, no corrosion of the reactor was observed. TABLE 1 Example 1 2 3 4 5 Reaction temperature 180 180 200 200 200 (° C.) NH₃/CF₃CH₂Cl ratio 2.7 4.0 4.0 4.0 4.0 (molar ratio) Conversion of CF₃CH₂Cl 90.4 90.5 97.5 97.5 93.2 (%) Composition of products (mol %) CF₃CH₃ 0.3 0.8 0.8 0.0 3.2 CF₃CH₂NH₂ 95.2 97.8 97.8 99.8 93.8 CF₃CH₂NH₂.HX 2.2 0.0 0.0 0.0 0.0 (CF₃CH₂)₂NH 2.0 1.0 1.1 0.1 2.3 Others 0.3 0.4 0.3 0.1 0.7

INDUSTRIAL APPLICABILITY

[0034] According to the present invention, by using a reaction solvent comprising an alkanediol as an essential component, the desired fluorinated alkylamine compound can be produced in high yield, while reducing the amount of by-products in the reaction product and preventing the reactor from corroding. Further, even if the reaction pressure is adjusted to be low, the desired fluorinated alkylamine compound can be obtained in adequate yield.

[0035] The entire disclosure of Japanese Patent Application No. 11-357781 filed on Dec. 16, 1999 including specification, claims and summary are incorporated herein by reference in its entirety. 

What is claimed is:
 1. A process for producing a fluorinated alkylamine compound, which comprises reacting a compound represented by F(CF₂)_(n)(CH₂)_(m)X (wherein X represents a chlorine atom, a bromine atom or an iodine atom, and n and m each independently represents an integer of at least 1) with NH₃ to produce a compound represented by F(CF₂)_(n)(CH₂)_(m)NH₂ (wherein n and m have the same meanings as the above), and is characterized by conducting the reaction in the presence of a reaction solvent comprising an alkanediol as an essential component.
 2. The process according to claim 1, wherein NH₃ is used at least four times by mol, relative to F(CF₂)_(n)(CH₂)_(m)X.
 3. The process according to claim 1 or 2, wherein the alkanediol is a C₂₋₁₀ alkanediol.
 4. The process according to claim 1, wherein the alkanediol is ethylene glycol and/or propylene glycol.
 5. The process according to claim 1, wherein n is 1, and m is
 1. 6. The process according to claim 1, wherein the reaction solvent essentially consists of an alkanediol.
 7. The process according to any one of claims 1 to 6, wherein X is a chlorine atom.
 8. The process according to claim 1, wherein the reaction pressure (gauge pressure) is from 0.5 to 10 MPa.
 9. The process according to claim 1, wherein the reaction pressure (gauge pressure) is from 1 to 5 MPa.
 10. The process according to claim 1, wherein a reaction crude product formed by the reaction is distilled to obtain a purified fluorinated alkylamine compound. 